Printing plate and method of making the same



v.Maly 8 1934'- T. E. RICHARDS 1,957,850

PRINTING P'LATEvAND METHOD OF MAKING THE SAME Filed oct. 2o, 1927 "/l/l AWM/ff /l/ wwf kann; u@

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Patented May V8, 19344 UNITED STATES PATENT OFFICE PRINTING PLATE AND METHOD 0F Maxl NG THE SAME Thomas Ernest Richards, Auckland, New Zealand Application October 20, 1927, Serial'No. 227,623

In New Zealand November 22, 1926 18 Claims.

` to the production of planographic plates for offse't printing purposes, especially for newspaper work, but it is nevertheless contemplated applying the invention to the preparationof lithographicplates of any type.- y

By the present invention, one is enabled to produce a planographic printing plate havingr a very strong, distinct and durable image which may be put in an oiset printing press, for example, and copies taken therefrom at a higher rate of speed and in greater -quantity than have heretofore been practicable in this class of work. 'I'he image -is deiined by a coating material which is made 'hard and ilrmly united with the .plate by partial penetration of the metal in a manner morev specifically pointed out hereinafter.

The invention accordingly comprises the several steps and relation and order of one or more I fof such steps with respect to each of the others,

and the printing plate possessing the features, properties, and the-relation of elements, which are exempliiied in the following detaileddisclosure, and the scope of the applicationof which Y will be indicated in the claims.

For a fuller understanding of the nature .and

- objects of the invention, reference should be had to the followingdetailed description takeny in connection with the accompanying drawing, in which:

Fig. 1 is an emerged cross section showing plate having an imagereceiving illm.

Fig. 2 shows a plate of the character shown in Fig. 1 having a developed image to which' is applied a coating containing an agent oi durable character in accordance with the invention; and Fig. 3 is a similar view showing the plate with `the image iilm removed to yield a lithographie printing plate of the present invention.

Referring now to the drawing, 10 denotes a grained metallic plate of any suitable ink-repellent metal, for example, zinc or aluminum, to

which is applied a illm 11 adapted to take an image, for example, a light sensitive film for receiving an image photographically. When an image has beenformed or developed by removing portions of the iilm from the plate, there remain upstanling portions as indicated at 12 in Fig. 2,

about which the image-reproducing material is applied. To this end, a coating 13 containing an agent of durable character is applied evenly over the plate, The plate when nally prepared'in 55 4metal by partial penetration thereof is indicated When producing lithographie plates photographically, there are in general four main steps to be followed, namely, (1) producing a photographic image upon a sensitized metal printing plate by exposing a photographic film thereon, (2) dissolving off the unexposed sensitive substance, (3) applying tothe plate a coating materialcapable oi' taking and holding a desired image form and of absorbing printers ink, (4) and nally developing the image on the plate according to any known or suitable method oi removing the exposed or relatively exposed portions of the sensitized substances.

'In the practice of the present invention, the coating material is made to have metal penetrating and adhering properties, and is so applied to theplate and the whole so treated by means `oi '.heat that the coating becomes highly adherent clean and efficient manner, while in the second the coating is lhardened andy firmly bonded with the plate. Y

Certain other steps which will be hereinafter Fish glue 16 ozs. Water 36 ozs. Ammonium bichromate 1% ozs. Ferrie ammonia citrate 1/2 oz.

Strong solution of ammonia 11/2 drams.

On this sensitized plate an exposure is made from a half-tone screened or line positive. (Obviously, a negative may be employed if' it is desired to make prints having theirlights and shadows reversed as compared with the original.) .The image is then developed by washing the plate with Water, which dissolves off the unexposed portions of the sensitized glue, leaving a negative image on the plate. The plate is next dried and afterwards coated with the penetrating inkabsorbing substance, as referred to above, which is a liquid or plastic material prepared with a suitable solvent or vehicle and a rugged material, such as asphaltum, to give it body and durability. The following formula for the coating material has been foundto give satisfactory results:J one gallon of pure turpentine (the solvent) is mixed with one pound of asphaltum (the body-giving material) and the mixture brought to the boiling point. This mixture is then combined with a second mixture consisting of one-hali`pound of transfer ink dissolved by heating in one quart of turpentine. To this is added a third or liquid mixture comprising one dram of a preparation 1consisting of oleic acid and ari essential oil, and

one dram of substantially pure oleic acid oil. The preparation of oleic acid and an essential oil preferred is that now sold on the open market under the tradename Elbagreen oil". This mixture has the property of penetrating and adhering to the plate, and being of a greasy nature, has affinity for printers ink, as is well known in the art. The addition of the transfer ink to this 'mixture increases the ailnity of the coating material.

The plate is coated with such material in any convenient uniform manner, for example by the whirling method, and then given the first heating, which is to a relatively moderate temperature, for example to 112 F. This temperature is suiilciently high to soften the coating but is not such as to crack the insoluble glue or film remaining on the plate, hence in general the figure given should not be exceeded. At this stage, the plate is entirely covered with some sort of material, the unexposed portions of the plate, which vwere washed clean by water being covered by the metal penetrating coating material, while the exposed portions are still protected by the insoluble glue or film. a

The plate is now finally developed, which is accomplished by immersing it in water, so that the surplus coating material overlying the remaining glue may be brushed away. It is then placed in a ten percent solution of phosphoric acid, so that the undeveloped glue or Elm, may

and well known in the art.

be dissolved or otherwise removed; after this the plate is washed with water; immersed in a ten percent solution of nitric acid for about twenty seconds; again washed with water; and immersed finally for one minute in a ten percent solution of phosphoric acid. l

The plate is now washed, brushed and dried and then given its second heating which is to a relatively high temperature, for example to a temperature of from '250 to 260 F. This heating is such as materially to assist the coating material to penetrate the surface of the plate and become hard and thoroughly bonded with the metal of the plate in a rm and durable manner. It is beneficial to continue such heating for several minutes to give ample time for accomplishing this effect. Care, however, should be exercised not to continue the second heating for such a length of time or at such intensity as to -cause injury to the plate.

When the plate has become cooled, it may be coated with a. solution of gum arabic and dried. The plate is now ready to be put in the printing press and run. .v

The image thus provided on the plate is a tough, closely adhering coating of ink-absorbing nature, the remainder of the plate being clean. The image is very durable, absorbs lnk readily, and gives lgood depth of color. In consequence the plate can be run at high speed and will produce more good prints than have heretofore been obtainable.

It will be understood that the particular ingradients mentioned in the foregoing description are not of the essence of the invention, and that some of the operations described, although practically necessary, are of a routine nature The invention is not limited to the particular procedure described, except as defined in the following claims. The term "film is used throughout in its generic sense, to 'designate any image-receiving substance.

I claim as my invention:

1. A lithographie printing plate which consists of an ink-repellent metallic sheet having a grained surface, and a coating comprising asphaltum, an ink-absorbing substance, oleic acid and an essential oil applied to said plate, shaped to have the configuration of a desired image and adhering closely to the plate, said coating having the property of being relatively hard and bonded to said plate with partial penetration of the metal.

2. A lithographie printing plate, which consists of e. sheet of ink-repellent metal having a grained surface intitially coated with a film, an image on said surface formed from said film, there being bare metal exposed about the image-form, and a coating comprising asphaltum, a transferink substance, oleic acid andan essential oil applied to said bare metal, said coating adhering closely to the metal plate, and having the property of penetrating the metal and' of softening when heated and when cold of being relatively hard and bonded to said plate.

3. The method of preparing lithographie printing plates, which comprises preparing a grained metallic plate having an image-form thereon, applying a coating material to -said plate about said image-form, said coating having metal penetrating properties, moderately heating said plate, removing the image-form, and then heating to a relatively high temperature.

a. The method of preparing lithographie printisa ing plates, which comprisespreparing a grained metallic plate having an image-form thereon, applying a coating material containing an agent of a durable character and a metal-penetrating oily agent to said plate about said image-form, moderately heating said plate, removing the material of said image-form, and then heating said plate to a relatively high temperature.

5. The method of preparing lithographie printing plates, which comprises preparing a grained metallic plate having an image-form thereon, app15/ing a coating material containing asphaltum and a metal-penetrating oily agent to said plate about said image form, moderately heating said plate, removing said image-form, and then heating to a relatively high temperature.

6. The method of preparing lithographie printing plates, which comprises preparing a grained metallic plate having an image-form thereon, applying a coating material to said plate containing an agent ofA a durable character, an-inkabsorbing substance and a metal-penetrating oily agent, moderately heating said plate, removing said image-form, and then heating said plate to a temperature such as to assist in causing said coating material to penetrate the metal of said plate and to become hard and firmly bonded therewith tvitl'lout injury to said plate.

v7. The method of preparing lithographie printing plates, which comprises preparing a grained metallic plate. having an image-form thereon, applying a coating material to said plate containing asphaltum, an ink-absorbing substance and a metal-penetrating oily agent, moderately heating said plate, removing said image-form, and then heating said plate to a relatively high temperature such as to assist in causing said coating material to penetrate the metal of said plate and to become hard and firmly bonded thereto without injury to said plate.

d. The method of preparing lithographie printing plates, which comprises preparing a grained metallic plate having an image-form thereon, applying a coating material to said plate containing asphaltum, a transfer-ink substance, oleic acid and an essential oil, heatingsaid plate to a moderate temperature, removing said imageform and then heating said plate to a relativelx high temperature such as to assist in causing the coating material to penetrate the metal and to become hard and firmly bonded thereto without injury to the plate.

9. The method of preparing lithographie printing plates, which comprises preparing a grained aluminum plate having an image-form thereon, applying -a coating material containing asphaltum, a transfer-ink substance, oleic acid and an essential oil, heating said plates to a temperature approximating 112 degrees F., then removing the image-form, and thereafter heating said plate to a temperature approximately in the neighborhood of from 250 to 260 degrees F.

10. A planographic metallic printing plate havy having its under-portions impregnated in the metal of the plate and constituting an embedded printing image.

11. A planographicmetallic printing plate having a finely grained surface and printing image areas thereon, said image areas being coated with a hardened ink-receiving material containing an asphaltum base penetrating and firmly impregnated in said metal plate.

12. A planographic metallic printing plate having a surface thereof penetrable by an asphaltum composition, said surface being grained to take water and having delineated areas of a permanent character corresponding to an image to be printed, said areas being covered by hardened asphaltum base material impregnated in said plate.

13. A planographic metallic printing plate having a finely grained surface and permanent delineated areas thereon corresponding to an image to be printed, said areas being impregnated by ink-receiving material containing a hardened asphaltum base.

14. A planographic metallic printing plate hav` ing a finely grained surface and having thereon permanent'delineated areas corresponding to an image to be printed, said areas beingimpregnated by ink-receiving portions of hardened asphaltum base material imbedded in the surface of the plate.

15. A planographic metallic printing plate having a finely grained surface capable of receiving water and permanent delineated areas thereon corresponding to an image to be printed, said areas being coated with hardened bituminous inkreceiving material having portions impregnated in said metallic plate, and constituting an ernbedded printing image.

16. A metal printing plate having ink-receiving portions of hardened asphaltum base material penetrating and embedded in the interstices of said plate. v

17. A planographic printing plate capable of being impregnated by an asphaltum ink-selective composition having ink-receiving portions of hardened asphaltum base material embedded in and penetrating said plate.

18. A planographic printing plate having a grained surface to take water and capable of being impregnatedr by anasphaltum ink-selective composition and ink-receiving portions of hardened bituminous material penetrating the plate.

THOMAS ERNEST RICHARDS.

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